Amplifier for sound-reproducing machine



F. T. SHACKLEFORD. AMPLIFIER FOB SOUND REPRODUQING MACHINE-S.

APPLICATION FILED DELx 1, I919.

Patent edSept. 6,1921.

I lilllll o! -i lill xlb 2 SHEETS-SHEET I.

O m I. m

e an a J w 0 0 .m &./// V//////////////A// AV////////////////// 9 3| 9, g 1 9 M 8 a s x I 1 UNITED STATES PATENT OFF-WE.

AMPLIFIER FOR SOUNILREPRODUCING MACHINE.

Specification of-Letters Patent.

Patented Sept. 6, 1921.

Application filed December 1, 1919. Serial No; 341,575.

To all whom it may concern: Be it known that I, FRANKLIN T. SHACK- LEFORD, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented certain new and useful Improvements in Amplifiers for Sound-Reproducing Machines; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. I b

This invention relates to improvements in sound reproducing machines, and has more particular reference to a sound amplifier or horn for such machine The principal object of the invention is to provlde an amplifier for phonographs or th ike which is such in construction that it will evenly diffuse and amplify the soundwaves passing therethrough and produce a clear mellow tone and one which will be true to the originalproduction.

Another object of the invention is to provide a device of this character which will be extremely simple, strong and durable in construction, easy and cheap to manufacture, and well adapted to the purpose for which .it is designed. a

With these and other objects in view, the invention consists of the novel features of construction, and the combination and arrangement of parts as will be hereinafter fully described and claimed.

In the accompanying drawings forming a part of the specification and in which similar reference characters designate like parts throughout the several views:

Figure 1 is a vertical sectional view through a portion of a phonograph, showing an amplifier constructed in accordance with this invention applied-thereto;

Fig. 2,,is a horizontal sectional view through the phonograph and amplifier taken on the plane indicated by the line 22 of Fig 1; ig. 3 is a front view of the amplifierdetached from the phonograph; J I

Fig. 4 is a front edge view of the bottom of the amplifier;

Fig. 5 is a side edge view of the l ottom of the amplifier; r

Fig. 6 is a longitudinal sectional view of l the bottom of the amplifier taken on the plane indicated by the line 6+6 of 4; and

Fig. 7 is a perspective view of the bottbm of the amplifier.

In the drawings, the numeral ldesignates a sound reproducing cabinet of the well known type. cluding the usual motor or driving mechanism 2 for imparting rotation to the turntable, a taper arm 3 which carries the soundbox, and a depending throat 4 which leads from the arm 3 to the horn or amplifier 5. These'parts are old and well known and constitute no part of this invention. The

invention resides in the specific construction and arrangement of amplifier or horn 5 which is to be hereinafter specifically described and claimed.

The amplifier referred to is preferably four sided and has its rear or inner end smaller in height and width than its forward or outer end so that the quadrangular walls are rhomboid shaped, that is, their This cabinet is shown as in forward and rear edges are parallel while their side edges are angularly disposed. The top 6 is larger than either of the two sides 7 and 8 or the bottom"9 and is made of spruce, or some other soft wood or material which is susceptible of being'easily vibrated by sound-waves. and the bottom 9 are made of mapleor some other hard wood or material which is capable of reflecting sound-Waves.

All of the walls of the amplifier, that is, the top 6, sides 7 and 8, and bottom 9, are beveled from opposite edges toward their middle'portions and fromone of their ends toward their other ends. This is preferably done by making the outer faces 0 the walls The side boards 7 and 8 flat, and by inclining their inner faces diagonally from their forward corners to the mid points of their rear ends. This makes 'the walls thicker at their middle portions along lines extendin at their side e ges, and also thicker at their rear ends than at their forward ends. The amount of bevel between the opposite 'faces of the walls of the amplifier is figured out longitudinally thereof than.

mathematically to correspond with a well known balanced scale used in graduating and regraduating violins and otherllke musical instruments.

The rear end of the amplifier is icy/acted in any suitable manner to a hollow neck 10 which leads to the-lower end of the tube 4.

This neck 10 connected as it is to the tube 4 forms a means for supporting the amplifier as the latter is not supported in any manner.

at its forward end. However, additional means for supporting the amplifier is provided, and this means consists of a pair of bars 11 which extend transversely across the cabinet 1, one above the neck 10 and the other below, and have their ends secured, preferably detachably, by means of screws 12, to cleats 13 fastened to the side walls of the cabinet. The cleats 13 are so located that when the screws 12 are screwed tight, the bars 11 will grip or clamp the neck 10 therebetween.

The sound-waves produced by the reproducing mechanism of the phonograph and passing through the arm 3, tube 1, and neck 10 into the sound-box 5, will seek the course of least resistance, and as they pass through the amplifier they will strike the various walls of the same and as said walls are thicker at their middle portions than at their edges, the sound-waves will be diffused laterally. The sides 7 and 8 and the bottom 9 of the sound box being made of hard Wood, reflect the waves onto the top 6, which being made of softer wood will easily vibrate andinsure effective amplification of the Waves. The bevel of the walls of the amplifier being from rear to front carries the waves clear as they pass through the same as the waves get weaker as they travel and the thinner the walls are the less resistance they offer. The result of the diffusion and amplification of thesound-waves produces a much clearer and more mellow tone than is capable of being produced by the usual type of the soundbox. The tones are also true to the original production.

From the foregoing description, taken in connection with the accompanying drawings, the construction, use and principles involved in this invention have been sufficiently set forth.

Various changes in form, proportion, and in the minor details of construction may be resorted to without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. A horn or amplifier for sound reproducing machines including a plurality of walls, the inner faces of which are beveled from opposite edges toward their middle portions, being also beveled from one of their ends to the opposite ends.

2. A horn or amplifier for sound reproducing machines including quadrangular walls, the inner faces of which are beveled from their forward corners diagonally to the mid points of their rear ends.

3. A horn or amplifier for sound reproducing machines comprising a truly horizontal bottom wall, an upwardly and forwardly inclined top wall and forwardly diverging side walls, the outer faces of the walls being flat and the inner faces being beveled from opposite edges toward their centers, all of the walls except one. being made of sound reflecting material, and said one wall being made of material susceptible of being easily vibrated by sound waves.

In testimony whereof I have hereunto set my hand.

FRANKLIN T. SHACKLEFORD. 

